Robotic therapy for heart failure
Researchers have resorted to robotics to help the 40 million people affected worldwide by heart failure.
Heart failure occurs when the heart muscle itself is diseased and cannot pump sufficient amounts of blood to meet the demands of the body. It's very debilitating and it robs sufferers of their quality of life and independence.
At the moment the only effective long term solution is a transplant, but only a tiny fraction of those people who need a heart transplant get one each year. This has prompted researchers to develop gadgets called ventricular assist devices - VADS, which can help to boost the heart's pumping ability but have some serious shortcomings.
Chiefly, because VADS are plumbed into the heart and blood vessels, there are problems with blood clotting on the foreign surfaces of the implants. Now National University of Ireland researcher Ellen Roche has helped to develop a new device, which fits snugly around the heart like a glove and solves some of these existing problems.
Presenting the design in the journal Science Translational Medicine, the gadget Roche has built is made from silicone and incorporates a series of tubes that work like artificial muscles powered by compressed air.
Implanted surgically around the heart, the rubber robot is coupled to an air supply which is synced with the natural heart rhythm so the robot squeezes the heart as it tries to beat, helping it to eject more blood.
Critically there is no contact between the implant and patient's blood supply, preventing the problems of clotting and the destruction of blood cells, which have dogged other ventricular assist device designs.
So far Roche and her colleagues have tested their implant in pigs, which mimic the human anatomy and physiology quite closely. The team simulated an episode of heart failure in an anaesthetised animal by using a drug to slow the heart and reduce its pumping ability.
"This dropped the flow through the aorta - the main blood vessel in the body - to about 50% of normal," says Roche. "With our robotic implant activated we were able to restore flow to normal levels."
The design of the new device is more complex that just a bag that can squeeze what is inside it. It's carefully fabricated so that as it contracts it also imparts a twisting motion, mimicking the natural change in shape that the heart undergoes as it beats. "It's like wringing out a dishcloth," says Roche. "There's both a squeezing and a twisting motion, and that's very important for heart function." The pumping contribution that it makes to both the right and left sides of the heart can also be individually adjusted to reflect the different forms and severities of heart failure experienced by patients.
At the moment the device is dependent on an air supply, which was used in this instance for experimental convenience, but, as they move towards clinical trials, Roche has her eye on alternatives that might make the gadget more practical for patients including using compressed helium, or even a fluid that could be stored in a small rucksack or belt.
Longer term "we need an internal power source, like a battery that can be charged through the skin, so patients won't have to be plugged into tubes and wires," says Roche.